1. Field of the Invention
This invention relates to curable epoxy resin systems. More particularly it relates to clear, non-yellowing epoxy resin formulations which cure to bind aggregate such as decorative pebbles to a surface.
2. Prior Art
Epoxy resins constitute a broad class of polymeric materials having a wide range of physical characteristics. The resins are characterized by epoxide groups which are cured by reaction with certain catalysts or curing agents to provide cured epoxy resin compositions with certain desirable properties. One such class of curing agents is the anhydrides. Another is the amines. It is known however that anhydrides and amines form clear coatings which yellow and deteriorate with time in the presence of sunlight. The problem of yellowing has been compensated for by the inclusion of UV absorbers or light stabilizers into the epoxy resin formulation. These additive materials are expensive which has prevented their use in amounts to cover large surfaces such as patios and driveways of residential houses. The problem has also been compensated for by using epoxy binders only on dark colored materials where the effect of yellowing is less detrimental to the appearance of the surface.
There is a need in the art for an inexpensive clear epoxy resin formulation for binding colored aggregate, particularly light colored materials, used outdoors and on surfaces exposed to sunlight which will not significantly yellow with time.